The present invention relates to a liquid crystal display device and, more specifically, to an active matrix type liquid crystal display device of a thin film transistor (TFT) type or the like and a manufacturing method for the same.
Two types of liquid crystal display devices are mainly used: one is a so-called vertical electric field type in which electrodes are disposed on the liquid-crystal-layer side of each of two substrates disposed in opposition to each other with a liquid crystal layer interposed therebetween; and the other is a lateral electric field type (in-plane-switching mode: IPS mode) in which lateral electric fields having components parallel to upper and lower substrates are applied to a liquid crystal gap therebetween. In either type, alignment films for controlling the initial alignment of liquid crystal molecules are respectively formed on the surfaces of the mutually opposed substrates that are closest to a liquid crystal layer, and the liquid crystal layer is sealed on four sides by a sealing material.
An area in which the sealing material is formed is called a peripheral area or a peripheral portion in contrast with an effective display area in which pixels are formed, and lines are led to a terminal portion through a layer underlying the sealing material on at least one side of the peripheral portion.
Japanese Patent Laid-Open Nos. 133787/2001 and 264793/2001 are publicly known as examples of the cross-sectional structure of the above-described peripheral portion.
The peripheral portion has two important roles, one of which is to fix upper and lower substrates with a sealing material, and the other of which is to lead lines. The former has the problem that its strength needs to be increased, and it is particularly important to increase the adhesion force between the sealing material and a layer to which the sealing material adheres. The latter has the problem that reliability needs to be ensured in a lead portion of each line, and it is particularly important to prevent the lead portion from coming into direct contact with a sealing portion. Therefore, the invention aims to provide a liquid crystal display device in which the two problems can be compatibly solved.
In addition, a liquid crystal display device in which an organic insulating film is constructed in a layer overlying lines and electrodes are constructed on the organic insulating film is disclosed in, for example, Japanese Patent Laid-Open No. 230378/1997. However, the present inventor has found out a new problem that in the case where an organic insulating film and a sealing material are stuck to each other, a layer to which to stick the sealing material is stuck is the organic insulating film itself, and in this case, the adhesion force therebetween lowers. Therefore, the invention also aims to provide a liquid crystal display device in which the above-described two problems can be compatibly solved even if the liquid crystal display device has an organic film layer formed in contact with an alignment layer in each pixel.
Further problems to be solved by and further objects to be achieved by the present application will become apparent in the present specification.